This invention relates to shearing of pile fabrics and more particularly to the shearing of carpet tufts and other pile in accordance with a pattern as the carpet is being fed so as to create a sculptured effect in the face or pile of the carpet.
In the art of manufacturing carpet, after the yarn has been tufted into a primary backing to form pile extending from the backing the stitches are locked therein by latex adhesive applied to the back of the primary backing, a secondary backing is thereafter attached and the latex is cured in an oven. Generally, especially in the case of cut pile carpet fabrics, the carpet is then fed through a shearing machine to tip shear the tufts. A conventional shearing machine comprises a rotating cylinder having a plurality of shearing blades which act against a stationary ledger blade. By shearing the tips, the surface of the carpet is leveled and made smooth.
Carpets may be tufted with a sculptured look by use of a pattern attachment in conjunction with the tufting machine. For example, carpet having pile tufts at a first level and loop pile tufts at a second level are well known, as are carpets having two levels of loop pile and two levels of cut pile. Such a pattern attachment operates by pulling back or back robbing yam from a prior stitch selectively to form the lower level pile. The cut pile tufts in these carpets additionally have to be tip sheared or the end product is not aesthetically appealing.
In Nakagawa U.S. Pat. No. 5,165,151 moveable fingers are controlled to lift the carpet backing and thus the pile at that location upwardly selectively closer to a cutter in accordance with a pattern so that selected pile is sheared. Since the carpet backing, which is relatively heavy, is moved, the patterning available with such apparatus is at best limited. A similar approach may have been tried where areas or surfaces of the carpet were raised to shear a portion of the pile in accordance with a pattern, but it does not appear to be in the patented art.
Clearly, since most carpet, at least cut pile carpet, are tip sheared, it is desirable to use the tip shearing procedure to provide a sculptured look rather than patterning in high-low fashion by the tufting process and subsequently tip shearing the pile.